2015A&A...579A...5H


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.03CEST23:19:01

2015A&A...579A...5H - Astronomy and Astrophysics, volume 579A, 5-5 (2015/7-1)

Clues to the formation of the Milky Way's thick disk.

HAYWOOD M., DI MATTEO P., SNAITH O. and LEHNERT M.D.

Abstract (from CDS):

We analyze the chemical properties of a set of solar vicinity stars, and show that the small dispersion in abundances of α-elements at all ages provides evidence that the star formation history (SFH) has been uniform throughout the thick disk. In the context of long-timescale infall models, we suggest that this result points either to a limited dependence of the gas accretion on the Galactic radius in the inner disk (R<10kpc) or to a decoupling of the accretion history and SFH due to other processes governing the interstellar medium in the early disk, suggesting that infall cannot be a determining parameter of the chemical evolution at these epochs. We argue that these results and other recent observational constraints - namely the lack of radial metallicity gradient and the non-evolving scale length of the thick disk - are better explained if the early disk is viewed as a pre-assembled gaseous system, with most of the gas settled before significant star formation took place - formally the equivalent of a closed-box model. In either case, these results point to a weak or non-existent inside-out formation history in the thick disk or in the first 3-5Gyr of the formation of the Galaxy. We argue, however, that the growing importance of an external disk whose chemical properties are distinct from those of the inner disk would give the impression of an inside-out growth process when seen through snapshots at different epochs. The progressive, continuous process usually invoked may not have actually existed in the Milky Way.

Abstract Copyright:

Journal keyword(s): Galaxy: abundances - Galaxy: evolution - Galaxy: disk - Galaxy: formation

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 HD 65907 PM* 07 57 46.9145300342 -60 18 11.051586167 6.17 6.17 5.60     F9.5V 161 0
2 Ross 892 PM* 10 27 24.2462412761 +01 24 00.192254880   11.55   10.8   sdF8 57 0
3 CD-43 6810 PM* 11 08 40.0960913641 -44 15 33.796755020   10.38 9.82     F8 53 0
4 HD 124785 PM* 14 16 57.3974526134 -50 16 52.885876176   9.22 8.67     F8/G0wF5 44 0
5 HD 141597 * 15 50 39.8507165616 -23 15 29.489703742   7.93 7.46     F5/6V 42 0
6 BD+08 3095 PM* 15 50 58.9335540844 +08 25 23.722428557   10.60   9.8   G2 71 0
7 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11533 0
8 HD 211038 PM* 22 14 38.2203018034 -15 49 06.715686022   7.44 6.54     G9.5IV-V 82 0

    Equat.    Gal    SGal    Ecl

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2020.07.03-23:19:01

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